Field of the Invention
This invention relates to cutting inserts and is specifically directed to an invertable, indexable, circular cutting insert which, when inverted, is designed to engage a cutting region longitudinally shifted from a cutting region that may be utilized on the opposite side of the insert. The invention also relates to a toolholder system utilizing the subject cutting insert mounted within a toolholder, such as a milling cutter.
Description of Related Art
Milling cutters for cutting and shaping metal workpieces have been known for many years. Such milling cutters generally comprise a cylindrical cutting body having a plurality of insert seats spaced around the periphery of the body. Cutting inserts are mounted within the insert seats and the insert seats are oriented so that the inserts mounted therein will effectively cut a workpiece when a cutter body is rotated along a longitudinal axis. In one embodiment, circular cutting inserts are used within the pockets and indexed at such time as a portion of the cutting edge is worn. Oftentimes, such circular inserts are not only indexable, but also invertable. As a result, when a particular edge is worn, the insert may be inverted to engage a cutting edge on the opposite side of the insert. In previous designs, however, the portion of the cutting edge that engaged the workpiece on one side of the cutting insert was longitudinally opposite the portion of the cutting edge on the opposite side which engaged the workpiece. As a result, when the cutting edge on the first side was utilized, the cutting edge and the region adjacent to the cutting edge was subjected to high temperatures and extreme conditions, which tended to degrade not just the cutting edge, but the material in the region of the cutting edge. When the insert was inverted and the cutting edge longitudinally opposite to the spent region was employed, the life of that cutting edge was reduced because the material in the region proximate to that cutting edge had been previously degraded through the use of the cutting edge on the opposing side.
A need exists to better utilize the cutting edges on a circular, indexable cutting insert that is reversible to minimize degradation of the region proximate to a cutting edge when the cutting insert is inverted.